Crankcase evacuation system



June 4, 1963 T. w. BOSLEY CRANKCASE EVACUATION SYSTEM Filed March 16,1962 INVEIIITCR. 7 /%dsfl& 5/ 3m ATTORNEYS United States Patent3,092,091 CRANKCASE EVACUATION SYSTEM Thomas W. Bosley, Birmingham,Mich. [610 W. 6th St., Santa Ana, Calif.) Filed Mar. 16, 1962, Ser. No.180,135 20 Claims. (Cl. 123-119) This invention pertains to a crankcaseevacuation system for an internal combustion engine and, in particular,to such a system for controlling and substantially reducing airpollution caused by crankcase emission, reducing oil consumption in theengine, and removing byproducts of combustion, such as water, corrosiveacids and the like, which otherwise tend to dilute the lubricating oilin the crankcase resulting in sludge deposits which ultimately causesticking piston rings, valves, valve lifters and extensive enginecorrosion.

During the operation of an internal combustion engine of thereciprocable piston and cylinder type conventionally employed onautomotive vehicles, a combustible mixture of air and hydrocarbon fuelis burned in the combustion chambers of the engine to perform work onthe pistons reciprocating therein. This combustion process produces avaporous mixture of unburned hydrocarbons or fuel, water, oil, corrosiveacids and the like, some of which vaporous mixture blows by the pistonrings and valve stem seals of the engine and are consequently termedblow-by gases or vapors. In one typical ventilated engine constructionin use today, part of the aforementioned blow-by gases or vapors entersthe air stream which is circulated through the crankcase by theventilation system, resulting in oxidation when the cool air comes intocontact with the warm oil vapors which is a primary source of sludge inthe engine. Furthermore, part of the blow-by vapors or gases willcondense as it travels down to the cooler area of the oil pan. Theproducts of such oxidation and condensation eventually drain into thelubricating oil and are commonly called a crankcase dilution or emulsionwhich, as is well known, is undesirable.

During certain engine operating conditions such as at high speeds or atengine overrun with the throttle valve closed, manifold vacuum willcause some of the blow-by vapors to be drawn up through the intake andexhaust valve stem seals and ports and to be carried into the firingchambers of the engine and out of the engine exhaust system producingunpleasant odors and smog. In colder weather, lower ambient airtemperatures reduce the ability of the crankcase ventilation system toremove water vapor and partly burnt fuel from the crankcase, therebyresulting in excessive oil consumption and frequent oil and filtercartridge changes are necessary. Thus, a high rate of crankcaseemission, air pollution and objectionable odors will occur.

To combat conditions such as those aforementioned, one practice has beento provide a vent tube type crankcase ventilation system including thewell known road draft or vent tube communicataing with the crankcase andatmosphere and so located that the forward motion of the vehicle overapproximately 20 miles per hour would cause a partial vacuum in thecrankcase and draw through atmospheric air to remove blow-by gases fromthe crank case. However, under normal road loads and speed, the incomingatmospheric ventilating air carries with it moisture, abrasive dusts,salts and other contaminants into and through the engine and, in thefinal analysis, such air and the blow-by gases picked up thereby aredirected out of the crankcase to the atmosphere through theaforementioned vent or road draft tube. Furthermore, at idle speeds, theblow-by gases within the crankcase will escape through the oil breathercap While at 3,092,091 Patented June 4, 1963 full throttle a pressurewithin the crankcase will force blow-by and oil vapors through allopenings in the crankcase causing bad odors, smog and an increase in oilconsumption.

To combat these difficulties and particularly the smog condition,another practice has been to provide a positive crankcase ventilationsystem which provides fresh atmospheric air to circulate through thecrankcase in a manner similar to the vent rtube type systemaforedescribed. However, instead of the ventilating air being dischargeto atmosphere, it is returned to the intake manifold by means of aconduit connecting the engine crank case to the intake manifold througha regulator or control valve which regulates the amount of air flowtherethrough to meet changing operating conditions in the engine. Such apositive crankcase ventilation system has been found to give goodresults when used on a new engine because each such positive system iscarefully engineered for each engine design and with particular regardto carburetion and manifold conditions thereof. Unfortunately, well overfifty percent of the vehicles in use on the roads today are at leastfours Years old and, because of excessive wear on piston rings, valvestem seals and the like, these older models have a particular blow-byproblem wherein the positive crankcase type of ventilation systemaforementioned is incapable of handling the added blow-by emission. Infact, it may be said that a given positive crankcase ventilation systeminstalled on a new car will, after the car ages three or four years, beonly about fifty percent as effective as when new in reducing smog dueto crankcase emission. Furthermore, even on a. new car which isgenerally operated at turnpike speeds, the regulator or control valverequires constant cleaning to remove sludge.

in such positive crankcase ventilation systems used in conjunction withan air tight or sealed crankcase system, the regulator or control valvemaintains a partial vacuum on the crankcase at idle and road loads.However, under certain engine operating conditions such as duringdeceleration or preparing to idle, the blow-by gases being drawn intothe intake manifold dilute and prevent the build-up of a sufl'lcientvacuum or pressure differential to close the regulating valve causingcarburetion difiiculties such as misfiring and sometimes stalling. Atfull throttle, the blow-by flow rate often exceeds the capacity of thepositive ventilation system resulting in a high pressure build-up in thecrankcase. This pressure may force the lubricating oil and blow-by gasesout through the main bearing seals, gaskets, dipstick tube, backflowoutlet and all other points of escape to the atmosphere resulting inexcessive air pollution and high oil consumption. Furthermore, due tothe high'crankcase pressure aforementioned, some oil and water vapor maycollect in the regulating valve and conduit associated therewith whichare exposed to ambient temperature resulting in condensation thereof toform a sludge and varnish. This sludge and varnish results in stickingof the regulating or control valve and its cooperating valve seat, andsticking of the exposed return spring thereof. Consequently, the valvemust be cleaned or replaced constantly.

It is, therefore, a principal object and feature of this invention toprovide an improved crankcase evacuation system which solves these andother problems in the prior art.

It is yet another obiect and feature of this invention to provide acrankcase evacuating system operable in conjunction with a substantiallyair tight or sealed crankcase of an internal combustion engine toeffectively remove blow-by gases therefrom and supply them through theintake manifold means of the engine for reburning within the combustionchambers thereof, thereby controlling and substantially reducingsmog-producing crankcase emission while avoiding the necessity ofsupplying fresh ambient air to the crankcase to substantially eliminatethe sludge forming oxidation action thereof.

It is yet another object and feature of this invention to provide acrankcase evacuating system for an internal combustion engine comprisingan evacuating conduit means including a control valve thereincommunicating blow-by vapors within the engine crankcase to the intakemanifold means of the engine, the aforementioned control valve having afirst position closing communication between the crankcase and theintake manifold means and a second position opening communicationtherebetween in response to a pressure signal generated anteriorly ofthe throttle valve located in the intake manifold means, whereby anexcessive volume of blow-by gases will not be supplied to the air andfuel mixture within the intake manifold means during cranking or idleoperation of the engine so as not to lean out the air-fuel mixture underthese conditions.

It is yet another object and feature of this invention to provide acrankcase evacuating system including evacuating conduit means andcontrol valve means as aforementioned further characterized in that thecontrol valve means includes a control spring normally biasing thecontrol valve to its closed position and adapted to be overcome by theaforementioned pressure signal to open the conduit means in response toa predetermined absolute pressure drop or vacuum increase anteriorly ofthe throttle valve, and wherein said control spring is completelyisolated from all blow-by and other vapors passing through theevacuating conduit means to prevent sticking and malfunctioning thereof.

It is yet another object and feature of this invention to provide acrankcase evacuating system of the type aforementioned including anevacuating conduit means and control valve therein further characterizedby means, preferably but not necessarily engine temperature responsive,for preventing communication of the inlet manifold means and the controlvalve means below a predetermined engine temperature.

It is yet another object and feature of this invention to provide acrankcase evacuating system of the type aforementioned including controlvalve means further characterized by adjustable bypass means forbypassing the control valve means at certain engine operatingconditions, such as at idle or during cranking of the engine, to imposeunder such conditions a predetermined minimum vacuum within thecrankcase to draw blow-by vapors therefrom to the intake manifold meanswithout pulling an excessive amount which would lean the fuel mixtureunder such conditions to an undesirable extent.

It is yet another object and feature of this invention to provide, incombination with a crankcase evacuating system of the typeaforementioned, an idle bypass and crankcase pressure control valvemeans communicating the evacuating conduit means with atmosphere,preferably through the air cleaner of the engine, said valve means beingoperable at all engine operating conditions, particularly at idle andcranking engine conditions, to prevent ambient atmospheric air fromentering the evacuating conduit means whereby blow-by gases may beevacuated from the crankcase through the bypass conduit meansaforementioned to the intake manifold means, and further operableautomatically to a position communicating the evacuating conduit meanswith atmosphere in response to crankcase back pressures in excess of apredetermined maximum.

It is yet another object and feature of this invention to provide anequalizer valve means communicating with the aforementioned evacuatingconduit means and atmosphere, again preferably through the engine aircleaner, and which equalizer valve means is normally closed but willopen automatically in response to a predetermined maximum amount ofvacuum within the crankcase to supply atmospheric air under pressurethrough the evacuating conduit means and past the control valve means tothe intake manifold means, thereby providing an unthrottled air chargeunder corresponding load conditions increasing the efficiency ofcombustion within the combustion cylinders of the engine, preventing thevacuum within the crankcase from exceeding a predetermined maximum toinsure the prevention of oil vapor pullover from the crankcase into theevacuating conduit means, diluting hydrocarbons being expelled from theengine exhaust system and giving more evacuation capacity at high speedoperation.

It is yet another object and feature of this invention to provide, in anengine crankcase evacuating system including an evacuating conduit meansconnecting the crankcase to the intake manifold means of the engine, acondensing or settling chamber in the lowest portion of the evacuatingconduit means to trap various emission byproducts of combustion andremove same from the blowby hydrocarbon gases passing through theevacuating conduit means to the intake manifold means of the engine.

These and other objects, features and advantages of the invention willappear more fully hereinafter as the description of the inventionproceeds, and in which reference is made to the drawing in which:

FIGURE 1 is a view, partially fragmentary and schematic, illustrating apreferred embodiment of the invention as mounted on an internalcombustion engine; and

FIGURE 2 is a exploded and enlarged view of various components of thesystem illustrated in FIGURE 1.

Referring now to the drawings, the numeral 10 generally indicates aninternal combustion engine of the type typically employed withautomobiles and comprising the usual engine block 12 and cooperating oilpan 14 forming a substantially sealed or air tight crankcase 16 in whichthe crankshaft 18 is mounted in a conventional manner. The enginefurther includes according to conventional practice a plurality ofcombustion chambers each of which includes a cylinder 20 in which thepiston 22 is reciprocably mounted and suitably connected to thecrankshaft, the usual inlet valves 24, exhaust valves (not shown), sparkplugs 26 and the usual cover member 28, including a substantially sealedoil filler cap 30, for the valve gearing.

An intake manifold means indicated generally at 32 is provided forsupplying an air and fuel charge to the respective combustion chambersof the engine, and comprises the usual intake manifold 34 including ariser on which the carburetor construction indicated generally at 36 andincluding the throttle valve 38 may be mounted in any conventionalmanner. An air cleaner assembly is indicated generally at 40 as beingmounted above the carburetor construction 36 in communication therewithfor supplying a filtered charge of air to the intake manifold means.Furthermore, the numeral 42 schmatically represents a conventionalengine temperature responsive automatic choke mechanism connected in theusual manner through the thermally conductive heat conduit 44 to theusual exhaust manifold 45, whereby the choke is positioned automaticallybetween opened and closed positions in response to engine temperature aswill be readily appreciated by those acquainted with this art.

The crankcase evacuation system of the present invention comprises anevacuating conduit means or tube 46 connected between a passage 48 inthe engine block 12 communicating with the sealed crankcase 16 and,through the control valve means indicated generally at 50, to the intakemanifold 34 posteriorly of the throttle valve 38. A condensing orsettling chamber 52 including one or more suitably positioned bafilemeans 54, by way of example, is interposed in the lowest portion of theevacuating conduit means 46 between the engine block 12 and controlvalve means 50. As will appear more fully hereinafter, in response to avacuum imposed within the sealed crank case 16 as communicated from theintake manifold 34 through the control valve means 50, blow-by vapors ofunburned hydrocarbons or fuels as well as heavier vaporous emulsioncomponents such as water, corrosive acids and the like flow from thecrankcase into the evacuating conduit means 46. As a result, since theevacuating conduit means and condensing chamber are exposed to ambienttemperatures, the heavier vaporous emulsion components condense andsettle within the condensing chamber for subsequent complete removal,while the lighter reburnable hydrocarbons still in vaporous form pass onthrough the evacuating conduit means and to the intake manifold forreburning in a manner to be described. While the condensing chamber 52has been illustrated in the drawing as including a lower drain valve fordraining same, it will be readily apparent that the condensate collectedwithin the chamber can be removed in any suitable manner.

The control valve means 50 comprises a valve body 56 adapted to 'besuitably connected, as by the threadable connection indicated at 58, toa wall of the intake manifold 34 posteriorly of the throttle valve 38.The valve body further includes a first passage 60 terminating in avalve seat 62 communicating with the intake manifold as aforedescribed,a second passage 64 angularly related, as at right angles as shown inFIGURE 2, to the first passage 60 and connected to one end of theevacuating conduit means 46, and a third passage 66 which may beopposite the second passage 64 and connected through a conduit means 68to a valve assembly indicated generally at 70 and preferably, althoughnot essentially, located within the air cleaner assembly 48.

A pressure housing or chamber 72 is provided on the valve body 56opposite the passage 60, and has secured therein the periphery of aconventional flexible diaphragm member 74 to which there is secured thestem 76 of a control valve member 78. The valve stem 76' slidably passesthrough a suitable sealed joint 80 in the pressure housing or chamber,whereby the flexible diaphragm divides the pressure chamber 72 into afirst pressure signal chamber 82 on one side of the diaphragm and asecond pressure signal chamber 84 on the other side thereof. A pluralityof apertures 86 formed in a wall portion of the pressure chambercommunicate ambient atmospheric pressure with the first pressure signalchamber 82, while the control spring 88 is mounted in the secondpressure signal chamber 84 to normally bias the valve member 78 to aclosed position on valve seat 62 as illustrated in FIGURE 2; that is,the force of the control spring 88 is suitably selected so as toovercome ambient atmospheric pressure in signal chamber 82 to alwaysbias the valve member 78 to the closed position illustrated. However,the valve member 78 is movable to the right in FIGURE 2 completely offof its seat 62 in response to the imposition of a predetermined lowabsolute pressure or, otherwise speaking, sufficiently high vacuumwithin the second pressure signal chamber 84, whereby ambientatmospheric pressure in the first signal chamber will overcome thecontrol spring.

This predetermined low absolute pressure or predeterminedly high vacuumis adapted to be transmitted to the second signal chamber 84 throughpressure signal conduit means 90 communicating with a port 92 in anengine temperature responsive enclosed thermally conductive heat chamber94, a second portion or continuation of the pressure signal conduitmeans 90 being connected between another port 96 in the heat chamber anda port 98 in the intake manifold means 32 anteriorly of the throttlevalve 38. The heat tube 44 previously described and associated with theautomatic choke mechanism 42 of the carburetor construction is welded orotherwise secured in thermally conductive relation with an exterior wallportion of the heat chamber 94 whereby heat conducted to the heatchamber controls the operation of a suitable temperature responsivemember, such as the conventional bimetallic element indicated at 109,suitably mounted within the heat chamber and having one end thereofequipped with a valve plug 102 adapted to open or close the port 96. Asa consequence, an absolute pressure or vacuum signal is incapable ofbeing communicated from the port 98 in the intake manifold means 32 tothe second pressure signal chamber 84 of the control valve means 50below any desired predetermined engine temperature. However, after adesired predetermined engine temperature is reached, it will beunderstood that the temperature responsive bimetallic element E08 willrespond to disengage the valve plug 102 from the port 96, therebyresulting in the pressure signal at the port 98 in the intake manifoldmeans being communicated with the second pressure signal chamber 84 inthe control valve means 50.

The valve body 56 further includes a bypass passage 104 around thecontrol valve seat 62 in the closed position of FEGURE 2. Suitable meanssuch as the adjustable threaded screw 106 is preferably employed toadjust the bipass flow around the control valve seat in its closedposition for reasons and in a manner to appear more fully hereinafter.Furthermore, the valve body is provided with a deflector plate 108suitably apertured to slidably receive the valve stem 76, and positioneddirectly in front of the first valve body passage 60 comrnunieating withthe intake manifold 34 and relative to the second valve body passage 64communicating with the sealed crankcase whereby, in the event of abackfire and flame attempting to pass from the intake manifold throughthe passage 60 to the interior of the valve body 56, such backfire orflame will be deflected positively away from the valve body passage 64thereby avoiding the danger of any fire resulting within the crankcaseof the engine. Finally, the valve body may also be provided with aconnection indicated at 110 communicating with the passage 60 and theintake manifold for driving various manifold vacuum operated accessorieson the vehicle.

As previously described, the conduit means 68 comrnunicates the thirdpassage 66 of the control valve body 56 with the valve assembly 70preferably, although not necessarily, located within the interior of theair cleaner assembly 40. The valve assembly 70 comprises a body member112 including a cage 114 confining a crankcase pressure control valve116 in the form of the well known plate type gravity check valve. In theposition illustrated in FIGURE 2 of the drawings, the gravity checkvalve 116 closes the port 118 in the cage 114 and prevents communicationof atmospheric air pressure, in this case through the air cleanerassembly, with the conduit 68. However, in the event that the valve 116is shifted off of port 118, the conduit 68 and evacuating conduit means46 will be communicated with atmosphere through one or more ports 12!)in cage 114. As will appear hereinafter, the gravity check valve isnormally in the position illustrated in FIGURE 2 during idling, crankingand normal loading conditions of the engine, but will operate to itsopen position to vent the passage means 68 and evacuating conduit means46 to atmosphere in response to a predetermined absolute pressure orminimum vacuurn within the crankcase 16 as will result, for example,from slight back pressures in the crankcase which may occur at fullthrottle of the engine and high speeds. Naturally, with the valveassembly 70 located interiorly of the air cleaner assembly 40 apreferred and aforementioned, blow by gasses so vented from the conduit68 and through the valve 116 will be drawn from the air cleaner assemblyback into the intake manifold 34 while the engine is operating. Underidling conditions of the engine in which the throttle valve 38 isclosed, and as will appear more fully hereinafter, a relatively highabsolute pressure or low vacuum anteriorly of the throttle valve 38 inthe intake manifold means 32 is insufiicient to operate the diaphragm 74to open the control valve member 78. Under these circumstances, apredetermined minimum vacuum is drawn within the crankcase through theevacuating conduit means 46 and bypass passage means 104 of the controlvalve means 50 to insure a predetermined minimum flow of blow-by gasesin the system even at idle. Under idling conditions as aforementioned,the gravity check valve 116 prevents the ingress of atmospheric airthrough the passage 68 to the bypass passage means to prevent dilutionor leaning of the idle combustion mixture.

Under certain engine conditions, as for example as the engine is beingdecelerated and the throttle valve has almost reached its closedposition illustrated in the drawings, manifold vacuum will reach a peakvalue which, unless otherwise compensated for, can result in theimposition of an extremely high manifold vacuum or relatively lowabsolute pressure in the sealed crankcase 16 which can result in oilvapor pull-over; that is, drawing over into the evacuating conduit means46 an undesired and inordinate amount of oil vapors which should beretained within the crankcase for lubricating purposes. This conditioncould be prevented by restricting the blow-by flow capacity of theevacuating system, but this would in turn restrict overall operatingefficiency. Hence, in accordance with the preferred way of preventingthis condition from occurring, the valve assembly 70 also includes aspring loaded one way equalizer check valve means or plate 122 normallybiased by its spring to a closed position over the port 124 in valvebody 112 communicating with the interior of the air cleaner assembly 40as illustrated in FIGURE 2 of the drawing. In the event that engineoperating conditions result in a peaking of manifold vacuum asaforedescribed, it will be readily apparent that the control valvemember 78 i fully off its seat 62 due to the pressure signal in theconduit means 90. At this time and under these conditions, the oil vaporpull-over problem aforementioned is presented due to the excessive,relatively speaking, manifold vacuum imposed on the crankcase 16 throughthe evacuating conduit means 46. To prevent the absolute pressure in thecrankcase from decreasing below a predetermined minimum or, otherwisestated, the manifold vacuum in increasing above a predetermined maximum,the spring biased equalizer valve means 122 is set to open at thedesired pressure level to provide an unthrottled charge of fresh ambientair through the conduit means 68 and control valve means 50 into theintake manifold 34 posteriorly of throttle valve 38. For example, if itis desired to limit the vacuum within the sealed crankcase 16 to a valuenot to exceed approximately five inches of mercury, the equalizer valveis set to open at this value whereby any tendency of the vacuum toincrease therebeyond within the crankcase is compensated for by theequalizer valve opening and a fresh charge of ambient air provided tothe manifold. Furthermore, under these conditions, the fresh unthrottledcharge of ambient air adds to the elficiency of combustion within thechambers further contributing to the overall economy of the engine, anddiluting the hydrocarbons being expelled from the engine exhaust system.

As will now be apparent from the foregoing description, the blow-by andemission vapors contained within the engine crankcase are adapted to becompletely evacuated through the evacuating conduit means 46. As thesevapors are so evacuated, the heavier emulsion factors including water,corrosive acids and other harmful constituents impinge upon and withinthe baffled condensing chamber 52 which is cool, relative to the engine,result ing in condensing of these undesirable emulsion constituents forsubsequent removal from the condensing chamber as previously described.Furthermore, in view of the fact that the condensing chamber is locatedin the low spot or point in the evacuating conduit means 46, any ofthese emulsion constituents which may be able to pass by the bafilemembers or their equivalent will tend to condense posteriorly of thecondensing chamber and run back into said chamber. The reburnablelighter fractions or hydrocarbons do not condense but are pulled undervacuum pressure along the evacuating conduit means and pass the opencontrol valve means 50 into the intake manifold means. Thus, undergeneral running conditions of the vehicle engine, blow-by gases andvapors and emulsion constituents are completely evacuated orsubstantially so from the engine, and the undesirable emulsionconstituents permanently separated and removed from the lubricating oilwithin the system while the reburnable hydrocarbons are returned forreburning within the combustion chambers.

In particular, it will be noted that the pressure signal for opening thecontrol valve means 50 is connected to the intake manifold meansanteriorly of the throttle valve 38. In view of this construction, andthe control spring 88, the control valve member 78 remains closed on itsseat as illustrated in FIGURE 2 under cranking and idling conditions ofthe engine. As a result, the blowby gases passing into the control valvemeans are prevented from diluting or leaning the fuel-air mixture underthese conditions to prevent upsetting carburetion of the engine andpossible stalling thereof. However, the adjustable bypass passage 104 ispreset so that under idling conditions there is a sufficient vacuumimposed upon the crankcase 16 to remove blow-by vapors therefrom. Undersuch idling conditions, for example, the spring loaded equalizer valvemeans 122 is biased to a closed position, while the gravity check valveconstruction 116 is closed over the port 108 so as to prevent the entryof additional air into the evacuating system.

However, under certain engine operating conditions as, for example, atfull throttle, the control valve means 50 may close due to insufficientvacuum in the intake manifold means being communicated to the secondpressure signal chamber 84 thereof or, further by way of example, simplybecause of there being insufficient vacuum communicating with thepassage 60 of the control valve means to draw excess blow-by gases fromthe crankcase to the intake manifold. As a result, back pressures may begenerated within the crankcase which, upon reaching a predeterminedmaximum in terms of absolute pressures, will cause the gravity checkvalve 116 to lift off of its seat to discharge excess pressure fluid tothe air cleaner assembly 40. Furthermore, it might be mentioned that thesame back pressure conditions might occur at other than full throttle inthe example referred to above simply because the engine has not warmedup, thereby preventing signal pressure from communicating through theconduit means to the control valve means 50 to open the latter.

Furthermore, under certain extreme vacuum conditions, the equalizervalve means 122 is operable to open automatically to provide a freshunthrottled charge of air through the conduit means 68 and the passage60 in control valve means 50 to the intake manifold. Thus, and asaforedescribed by way of example, during deceleration of the engine inwhich the throttle valve is gradually closed but has not quite closed,the vacuum adjacent the throttle valve and the port 98 will reach apeak, relatively speaking, which is imposed through the open controlvalve means 50 and the evacuating conduit means 46 on the sealedcrankcase 16. To further prevent oil vapor pull-over, the springpressure of the equalizer valve is set to open at some predeterminedmaximum vacuum or minimum absolute pressure within the sealed crankcaseto provide the unthrottled charge of fresh air as aforementioned, and toprevent the vacuum within the crankcase from exceeding suchpredetermined maximum.

Also, and as will be readily apparent, the engine temperature responsivecontrol means 100 is provided to prevent opening of the control valvemeans 50 by blocking the pressure signal in the pressure signal conduitmeans 90 while the engine is cold, thereby preventing too lean a mixtureunder these cold engine conditions which could otherwise result inmisfiring or even stalling of the engine.

Finally, it will be noted that the control spring 88 of control valvemeans 50 is completely isolated and sealed from the various gasesflowable through valve body 56. Hence, such gases are unable to formsticky deposits on the spring thereby contributing to a long, troubleand maintenance free life for the latter.

While but one form of the invention has been shown and described, otherforms will now be apparent to those skilled in the art. Therefore, itwill be understood that the embodiment shown in the drawing anddescribed above is merely for illustrative purposes, and is not intendedto limit the scope of the invention which is defined by the claims whichfollow.

I claim:

1. A crankcase evacuating system for an internal combustion enginehaving a crankcase and intake manifold means including a throttle valve,said system comprising evacuating conduit means adapted to connect saidcrankcase to said intake manifold means posteriorly of said throttlevalve, and pressure operated control valve means in said evacuatingconduit means controlling the flow of vapor therein from said crankcaseto said intake manifold means, said control valve means being movablebetween a first position closing said evacuating conduit means and asecond position opening said evacuating conduit means in response to apredetermined absolute pressure in said intake manifold means anteriorlyof said throttle valve.

2. A crankcase evacuating system for an internal com bustion enginehaving a crankcase and intake manifold means including a throttle valve,said system comprising evacuating conduit means adapted to connect saidcrankcase to said intake manifold means posteriorly of said throttlevalve, control valve means in said evacuating conduit means controllingthe flow of vapor therein from said crankcase to said intake manifoldmeans, said control valve means being movable between a first positionclosing said evacuating conduit means and a second position opening saidevacuating conduit means, and means controlling movement of said controlvalve means between said positions including signal conduit meansadapted to connect said control valve means to said intake manifoldmeans anteriorly of said throttle valve.

3. A crankcase evacuating system for an internal cornbustion enginehaving a crankcase and intake manifold means including a throttle valve,said system comprising evacuating conduit means adapted to connect saidcrankcase to said intake manifold means posteriorly of said throttlevalve, pressure differential responsive control valve means in saidevacuating conduit means controlling the flow of vapor therein from saidcrankcase to said intake manifold means, said control valve means beingmovable between a first position closing said evacuating conduit meansand a second position opening said evacuating conduit means in responseto a predetermined pressure differential between atmospheric pressureand a signal pressure in said intake manifold means anteriorly of saidthrottle valve, and signal conduit means adapted to connect said controlvalve means to said intake manifold means anteriorly of said throttlevalve to communicate said signal pressure therebetween.

4. A crankcase evacuating system for an internal combustion enginehaving a crankcase and intake manifold means including a throttle valve,said system comprising evacuating conduit means adapted to connect saidcrankcase to said intake manifold means posteriorly of said throttlevalve, control valve means in said evacuating conduit means controllingthe flow of vapor therein from said crankcase to said intake manifoldmeans, said control valve means being movable between a first positionclosing said evacuating conduit means and a second position opening saidevacuating conduit means in response to a predetermined absolutepressure in said intake manifold means anteriorly of said throttlevalve, and means for preventing movement of said control valve means tosaid second position below a predetermined engine temperature.

5. In an internal combustion engine having a substantially sealedcrankcase and intake manifold means including a throttle valve, acrankcase evacuating system comprising evacuating conduit meansconnecting said crankcase to said intake manifold means posteriorly ofsaid throttle valve, pressure differential responsive control valvemeans in said evacuating conduit means controlling the flow of vaportherein from said crankcase to said intake manifold means, said controlvalve means being movable between a first position closing saidevacuating conduit means and a second position opening said evacuatingconduit means in response to a predetermined pressure differentialbetween atmospheric pressure and a signal pressure in said intakemanifold means anteriorly of said throttle valve, signal conduit meansconnecting said intake manifold means anteriorly of said throttle valveto said control valve means to communicate said signal pressuretherebetween, and means for preventing communication of said signalpressure with said control valve means below a predetermined enginetemperature.

6. A crankcase evacuating system for an internal combustion enginehaving a substantially sealed crankcase and intake manifold meansincluding a throttle valve, said system comprising evacuating conduitmeans adapted to connect said crankcase to said intake manifold meansposteriorly of said throttle valve, and equalizer valve means operableto supply atmospheric air to said evacuating conduit means upon thevacuum in said crankcase exceeding a predetermined maximum.

7. A crankcase evacuating system for an internal combastion enginehaving a substantially sefled crankcase and intake manifold meansincluding a throttle valve, said system comprising evacuating conduitmeans adapted to connect said crankcase to said intake manifold meansposteriorly of said throttle valve, and equalizer valve meansoperatively communicating said evacuating conduit means with atmosphere,said equalizer valve means having a closed position preventingcommunication between atmosphere and said evacuating conduit means andbeing movable to an open position to communicate atmosphere with saidevacuating conduit means upon the vacuum in the latter exceeding apredetermined maximum.

8. In an internal combustion engine having a substantially sealedcrankcase and intake manifold means including a throttle valve, acrankcase evacuating system comprising evacuating conduit meansconnecting said crankcase to said intake manifold means posteriorly ofsaid throttle valve, and equalizer valve means operatively communicatingsaid evacuating conduit means with atmosphere, said equalizer valvemeans having a closed position preventing communication betweenatmosphere and said evacuating conduit means and being movable to anopen position to communicate atmosphere with said evacuating conduitmeans upon the vacuum in the latter exceeding a predetermined maximum.

9. A crankcase evacuating system for an internal combustion enginehaving a substantially sealed crankcase and intake manifold meansincluding a throttle valve, said system comprising evacuating conduitmeans adapted to connect said crankcase to said intake manifold meansposteriorly of said throttle valve, and crankcase pressure control valvemeans operable to communicate said evacuating conduit means withatmosphere upon the absolute pressure in said crankcase exceeding apredetermined maximum.

10. In an internal combustion engine having a substantially sealedcrankcase and intake manifold means including a throttle valve, acrankcase evacuating system comprising evacuating conduit meansconnecting said crankcase to said intake manifold means posteriorly ofsaid throttle valve, control valve means in said evacuating con duitmeans controlling the flow of vapor therein from said crankcase to saidintake manifold, said control valve means being movable between a firstposition closing said evacuating conduit means and a second positionopening said evacuating conduit means in response to a predeterminedabsolute pressure in said intake manifold means anteriorly of saidthrottle valve, bypass conduit means bypassing said control valve meansto permit the flow of vapor from said crankcase to said intake manifoldmeans with said control valve means in said first position, andcrankcase pressure control valve means operatively communicating saidevacuating conduit means with atmos phere, said crankcase pressurecontrol valve means having a first position preventing communicationbetween said evacuating conduit means and atmosphere to maintain apredetermined minimum vacuum in said crankcase with said control valvemeans in its first position for flow of vapor through said bypassconduit means, and being movable to a second position communicating saidevacuating conduit means with atmosphere upon the vacuum in saidcrankcase exceeding a predetermined minimum.

11. In an internal combustion engine having a substantially sealedcrankcase and intake manifold means including a throttle valve, acrankcase evacuating system comprising conduit means extendingexteriorly of said engine and connecting said crankcase to said intakemanifold means posteriorly of said throttle valve, and pressuredifferential responsive control valve means in said evacuating conduitmeans controlling the flow of vapor therein from said crankcase to saidintake manifold means, said control valve means being movable between afirst position closing said evacuating conduit means and a secondposition opening said evacuating conduit means in response to apredetermined pressure differential between atmospheric pressure and asignal pressure in said intake manifold means anteriorly of saidthrottle valve.

12. The invention as defined in claim 11 further comprising means forpreventing communication of said signal pressure to said control valvemeans below a predetermined engine temperature.

13. The invention as defined in claim 11 further comprising equalizervalve means communicating said evacuating conduit means with atmosphere,said equalizer valve means being normally closed and operableautomatically to an open position to communicate air at substantiallyatmospheric pressure with said evacuating conduit means upon the vacuumin the latter exceeding a predetermined maximum.

14. The invention as defined in claim 12 in which said engine furtherincludes air cleaner means communicating with said intake manifold meansanteriorly of said throttle valve, and in which said equalizer valvemeans communicates said evacuating conduit means to atmosphere throughsaid air cleaner means.

15. The invention as defined in claim 11 further comprising bypassconduit means bypassing said control valve means to permit the flow ofvapor from said crankcase to said intake manifold means with saidcontrol valve means in said first position, and crankcase pressurecontrol valve means communicating said evacuating conduit means withatmosphere, said crankcase pressure control valve means having a firstposition preventing communication between said evacuating conduit meansand atmosphere to maintain a predetermined minimum vacuum in saidcrankcase with said control valve means in said first position or How ofvapor through said bypass conduit means, and being operableautomatically to a second position communicating said evacuating conduitmeans with atmosphere upon the absolute pressure in said crankcaseexceeding a predetermined maximum.

16. The invention defined in claim 14 in which said bypass conduit meansincludes adjustable throttling means.

17. The invention as defined in claim 14 in which said engine furtherincludes air cleaner means communicating with said intake manifold meansanteriorly of said throttle valve, and in which said crankcase pressurecontrol valve means communicates said evacuating conduit means toatmosphere through said air cleaner means.

18. The invention as defined in claim 11 in which said control valvemeans comprises a valve body including first and second portsrespectively communicating with said crankcase and said intake manifoldmeans, a valve seat within said valve body, a valve member cooperablewith said valve seat and being movable between said first positionengaged with said valve seat to close said evacuating conduit means andsaid second position disengaged therefrom to open said evacuatingconduit means, a pressure chamber in said valve body substantiallysealed from said valve seat, flexible diaphragm means mounted withinsaid pressure chamber and dividing the latter into first and secondpressure signal chambers on opposite sides of said diaphragm means,means operatively connecting said diaphragm means to said valve memberto move the latter between said first and second positions, meanscommunicating said first pressure signal chamber to atmosphericpressure, means communicating said signal pressure to said secondpressure signal chamber, and spring means in said pressure chambercontinuously biasing said valve member toward said first position.

19. The invention as defined in claim 18 further comprising defiectormeans within said valve body and positioned relative to said first andsecond ports so that any backfire entering said valve body through saidfirst port will be deflected away from said second port.

20. The invention as defined in claim 11 further comprising a chambercommunicating with said evacuating conduit means exteriorly of saidengine to collect condensate therefrom for subsequent removal.

References Cited in the file of this patent UNITED STATES PATENTS

1. A CRANKCASE EVACUATING SYSTEM FOR AN INTERNAL COMBUSTION ENGINEHAVING A CRANKCASE AND INTAKE MANIFOLD MEANS INCLUDING A THROTTLE VALVE,SAID SYSTEM COMPRISING EVACUATING CONDUIT MEANS ADAPTED TO CONNECT SAIDCRANKCASE TO SAID INTAKE MANIFOLD MEANS POSTERIORLY OF SAID THROTTLEVALVE, AND PRESSURE OPERATED CONTROL VALVE MEANS IN SAID EVACUATINGCONDUIT MEANS CONTROLLING THE FLOW OF VAPOR THEREIN FROM SAID CRANKCASETO SAID INTAKE MANIFOLD MEANS, SAID CONTROL VALVE MEANS BEING MOVABLEBETWEEN A FIRST POSITION CLOSING SAID EVACUATING CONDUIT MEANS AND ASECOND POSITION OPENING SAID EVACUATING CONDUIT MEANS IN RESPONSE TO APREDETERMINED ABSOLUTE PRESSURE IN SAID INTAKE MANIFOLD MEANS ANTERIORLYOF SAID THROTTLE VALVE.